Optical receptacle having stub capable of enhancing optical coupling efficiency and optical module installing the same

Abstract

The present invention provides an optical receptacle capable of reducing the optical coupling loss with the connector plug to be mated with the receptacle, and an optical module installing the receptacle. The receptacle of the invention includes an optical waveguide, a stub, and a body. The stub includes a first bore, into which the waveguide is disposed, and a second bore. The waveguide may be made of same material as that constituting the core of the optical fiber, and may have a substantially same diameter as that of the cladding. Thus, the aperture for coupling the optical fiber may be expanded.

1. An optical receptacle for receiving an optical connector plug that secures an optical fiber with a core and a cladding surrounding the core, and for connecting the optical fiber with an optical device including a light emitting device, said optical receptacle comprising:
 an optical waveguide made of material having a homogeneous refractive index; 
 a cylindrical stub with a uniform outer diameter, said stub including a first bore and a second bore continuous with said first bore, said first bore securing said optical waveguide therein at a location upstream of the optical fiber of an optical connector plug received by said optical receptacle, said second bore being at a location upstream of said first bore and downstream of the light emitting device of an optical device connected to an optical connector plug by said optical receptacle; and 
 a sleeve having a first portion and a second portion along an optical axis of said sleeve, said first portion of said sleeve receiving a portion of said stub and said second portion of said sleeve receiving an optical connector plug, 
 wherein said second bore of said stub has a diameter greater than a diameter of said first bore, and 
 wherein a length of said second bore along an optical axis of said stub is longer than a length of said first bore along said optical axis. 
 
   
   
     2. The optical receptacle according to  claim 1 ,
 wherein the diameter of said first bore of said stub is substantially equal to a diameter of the optical fiber at an interface between said first and said second bores. 
 
   
   
     3. The optical receptacle according to  claim 2 ,
 wherein said waveguide has a convex surface together with said stub at a side opposite to said second bore so as to physically come into contact with the optical fiber when the optical connector plug is inserted into said sleeve. 
 
   
   
     4. The optical receptacle according to  claim 1 ,
 wherein the refractive index of said waveguide is substantially equal to the refractive index of the core. 
 
   
   
     5. The optical receptacle according to  claim 1 ,
 wherein an interface between said first and said second bores of said stub together with said waveguide is inclined with respect to said optical axis of said sleeve. 
 
   
   
     6. The optical receptacle according to  claim 1 ,
 wherein said stub is made of zirconia. 
 
   
   
     7. The optical receptacle according to  claim 1 ,
 wherein said stub is made of metal. 
 
   
   
     8. The optical receptacle according to  claim 1 ,
 further comprising a sleeve cover and a bush, said bush being press-fitted between said stub in a side of said second bore and said sleeve cover such that said sleeve and said bush receive all of said stub and 
 wherein said sleeve cover covers said sleeve and said bush. 
 
   
   
     9. The optical receptacle according to  claim 1 ,
 wherein said waveguide is made of silica glass. 
 
   
   
     10. An optical module to be mated with an optical connector plug that secures an optical fiber therein, the optical module comprising:
 an optical receptacle including 
 an optical waveguide made of material having a homogeneous refractive index, 
 a cylindrical stub with a uniform outer diameter, the stub including a first bore and a second bore, continuous with the first bore, the first bore being filled with the optical waveguide, the second bore having a diameter greater than a diameter of the first bore, and 
 a sleeve having a first portion and a second portion along an optical axis of the sleeve, the first portion receiving a portion of the stub and the second portion receiving the optical connector plug; 
 an optical device including a stem for mounting a semiconductor optical device thereon and a cap for enclosing the semiconductor optical device co-operated with the stem; 
 a lens supported by the cap to focus light emitted from the semiconductor optical device; and 
 an alignment member arranged between the optical receptacle and the optical device to optically align the optical receptacle with respect to the optical device, 
 wherein the second bore is downstream of the semiconductor optical device and the lens, along the optical axis of the sleeve. 
 wherein the first bore is downstream of the second bore along the optical axis of the sleeve, 
 wherein the diameter of the second bore at a side opposite to the first bore, the diameter of the first bore at an interface with the second bore, and a length of the first bore are determined such that the lens focuses the light on a surface of the first bore, opposite to the second bore, 
 wherein a length of said second bore along the optical axis of said sleeve is longer than a length of said first bore along said optical axis. 
 
   
   
     11. The optical module according to  claim 10 ,
 wherein the waveguide secured in the first bore of the stub has a convex surface in a side opposite to the second bore so as to physically come into contact with the optical fiber when the optical connector plug is inserted into the sleeve. 
 
   
   
     12. The optical module according to  claim 10 ,
 wherein the first bore has a diameter gradually increasing from a surface that abuts against the optical fiber when the optical connector plug is inserted into the optical receptacle to an interface with the second bore. 
 
   
   
     13. The optical module according to  claim 10 ,
 wherein the second bore has a diameter gradually increasing from the interface with the first bore to a side opposite the first bore. 
 
   
   
     14. The optical module according to  claim 10 ,
 wherein an interface between the first bore and the second of the stub is inclined with respect to an optical axis of the sleeve by a predetermined amount. 
 
   
   
     15. The optical module according to  claim 10 ,
 wherein the optical receptacle further includes a sleeve cover and a bush, the sleeve cover covering the sleeve, the bush being press-fitted between the stub in a side of the second bore and the sleeve cover such that the sleeve and the bush receives all of the stub, and 
 wherein the alignment member fixes the sleeve cover thereto without fixing the bush and the stub. 
 
   
   
     16. The optical module according to  claim 10 ,
 wherein a length of the first bore of the stub along the optical axis of the sleeve is shorter than a length of the second bore of the stub along the optical axis of the sleeve.